Vehicle headlight

ABSTRACT

A plurality of lighting device units  30,  the light sources of which are light emitting elements  34,  are tiltably supported by a common unit support member  20,  so that optical axes of the plurality of lighting device units  30  are simultaneously adjusted. The projection lens  32  and the rectilinear propagation blocking member  38,  which compose each lighting device unit  30,  are integrated with each other as a light control member  40,  and this light control member  40  and the light emitting element  34  are individually attached to the unit support member  20.  Due to the foregoing, the lighting device structure can be made simple compared with the structure in which the completed lighting device unit is attached to the unit support member  20.

BACKGROUND OF THE INVENTION

The present invention relates to a vehicle headlight to form apredetermined light distribution pattern having a cutoff line at theupper end edge thereof, when light is irradiated by a plurality oflighting device units.

In general, a vehicle headlight can form a light distribution patternfor a low beam having a cutoff line at the upper end edge. Due to theabove constitution, while a driver in a vehicle running in the oppositedirection is not being given glare, the front visibility in of a driverwho drives a vehicle can be ensured as positively as possible.

JP-A-2003-123517 discloses a vehicle headlight that forms a lightdistribution pattern for a low beam by the irradiation of light sentfrom a plurality of lighting device units having light emitting elementsas the light sources.

When the lighting device of JP-A-2003-123517 is employed, it becomespossible to reduce the thickness of the lighting device. However, inthis case, it is necessary to adjust an optical axis of each of theplurality of lighting device units.

On the other hand, when such a constitution that a plurality of lightingdevice units are supported by a common unit support member is employed,it is possible to simultaneously adjust optical axes of a plurality oflighting device units by tilting the unit support member.

However, the above structure has the following problems. The unitsupport member attached with a plurality of lighting device units isfurther attached to a lamp body. Therefore, the lighting devicestructure becomes complicated.

SUMMARY OF THE INVENTION

The present invention has been accomplished in view of the abovecircumstances. It is an object of the present invention to provide avehicle headlight to form a predetermined light distribution patternhaving a cutoff line at the upper end portion, when light is irradiatedby a plurality of lighting device units, the vehicle headlightcharacterized in that: the thickness of the lighting device is reduced;and the optical axes of the plurality of lighting device units can besimultaneously adjusted without making the structure of the lightingdevice complicated.

In the invention of the present patent application, when each lightingdevice unit is divided into predetermined components and attached to acommon unit support member, the above object can be accomplished.

The present invention provides a vehicle headlight to form apredetermined light distribution pattern, at the upper end edge of whicha cutoff line is formed, when light is irradiated by a plurality oflighting device units, characterized in that: the plurality of lightingdevice units are supported by a common unit support member; eachlighting device unit has a projection lens, a light emitting elementarranged at the rear of the rear side focus of the projection lens and arectilinear propagation blocking member, which is arranged in theneighborhood of the rear side focus, for blocking a rectilinearpropagation of a portion of light emitted from the light emittingelement so as to form the cutoff line; the projection lens and therectilinear propagation blocking member are integrally formed as a lightcontrol member; and the light control member and the light emittingelement are individually attached to the unit support member.

As long as the light distribution pattern has a cutoff line at the upperend edge, the above “predetermined light distribution pattern” may be alight distribution pattern for a low beam. Alternatively, the above“predetermined light distribution pattern” may be a light distributionpattern composing a portion of the light distribution pattern for a lowbeam. In the latter light distribution pattern, the light distributionpattern for a low beam can be formed as a compound light distributionpattern in which this light distribution pattern is compounded with alight distribution pattern which is formed by the irradiation of lightsent from the lighting device unit except for the above plurality oflighting device units.

The above “light emitting element” means an element-shaped light sourcehaving a light emitting portion for emitting light like a substantialspot-shape. The type of the element-shaped light source is notparticularly limited. For example, a light emitting diode or a laserdiode can be adopted.

Concerning the above “rectilinear propagation blocking member”, as longas it can form a cutoff line and block a rectilinear propagation of aportion of light emitted from the light emitting element, the specificstructure of the rectilinear propagation blocking member is notparticularly limited. For example, the rectilinear propagation blockingmember can be comprised of a light-shielding member or a reflectingmember. In this case, “light emitted from the light emitting element”may be direct light sent from the light emitting element. Alternatively,“light emitted from the light emitting element” may be light reflectedon the other optical member or light transmitted through the otheroptical member.

Concerning the above “light control member”, as long as the projectionlens and the rectilinear propagation blocking member are integrallyformed in it, the light control member maybe a one-body molded productor an insertion molded product. Alternatively, the light control membermay be an integrated body in which the projection lens and therectilinear propagation blocking member are integrated with each otherinto one body by means of welding (for example, laser welding) oradhesion.

As explained above, in the vehicle headlight of the present invention, apredetermined light distribution pattern having a cutoff line at anupper end edge is formed by the irradiation of light sent from aplurality of lighting device units, the light sources of which are lightemitting elements. Therefore, the thickness of the lighting device canbe reduced.

In the vehicle headlight of the present invention, a plurality oflighting device units are supported by a common unit support member.Therefore, when this unit support member is tilted, the optical axes ofthe plurality of lighting device units can be simultaneously adjusted.

In the vehicle headlight of the present invention, the projection lensand the rectilinear propagation blocking member, which compose eachlighting device unit, are integrated with each other into one body sothat they can be composed as a light control member. Since this lightcontrol member and the light emitting element are individually attachedto a unit support member, the following operational effects can beprovided.

In a lighting device unit composed in such a manner that a portion oflight emitted from a light emitting element is prevented frompropagating straight by a rectilinear propagation blocking memberarranged in the neighborhood of the rear side focus of a projectionlens, in order to form a clear cutoff line at a predetermined positionwith high accuracy, it is very important to ensure the accuracy of thepositional relation between the projection lens and the rectilinearpropagation blocking member. On the other hand, the accuracy of thepositional relation between them and the light emitting element is notso important.

Therefore, as described in the present invention, when the projectionlens and the rectilinear propagation blocking member, the accuracy ofthe positional relation of which must be high, are integrally formed asa light control member and when the light control member and the lightemitting element are individually attached to the unit support member,the lighting device unit can be completed without affecting the lightdistribution performance of the lighting device unit. When thecomponents of the lighting device unit are individually attached to theunit support member, the lighting device structure can be made simplecompared with a case in which the completed lighting device unit isattached to the unit support member.

As described above, according to the present invention, in a vehicleheadlight composed so that a predetermined light distribution patternhaving a cutoff line at an upper end edge can be formed by theirradiation of light sent from a plurality of lighting device units,while the thickness of the lighting device is being reduced, the opticalaxes of the plurality of lighting device units can be simultaneouslyadjusted without making the lighting device structure complicated.

When the unit support member is composed of a die-cast product in theabove constitution, the following operational effects can be provided.

When the light emitting element of each lighting device unit emitslight, heat is generated. However, since each light emitting element isattached to the unit support member composed of a die-cast product, heatgenerated by each light emitting element can be quickly transmitted tothe unit support member, the heat capacity of which is large, by theaction of heat conduction. Due to the foregoing, a temperature rise inthe light emitting element can be suppressed. Therefore, it is possibleto effectively prevent the luminous flux of the light emitting elementfrom being decreased. It is also possible to prevent the color ofemitted light from becoming discolored.

When the light control member is composed of an insertion molded productin the above constitution, the following operational effects can beprovided.

When the insertion molding is conducted after the projection lens hasbeen inserted, it is possible to integrate the projection lens and therectilinear propagation blocking member by the insertion molding afterthe projection lens has been previously formed as a single body. Due tothe foregoing, after the profile accuracy of the projection lens hasbeen sufficiently ensured, the accuracy of the positional relationbetween the projection lens and the rectilinear propagation blockingmember can be sufficiently enhanced.

In the above constitution, when each of at least some lighting deviceunits in the plurality of lighting device units includes a reflector forreflecting a beam of light, which is sent from the light emittingelement, forward so that the beam of light can be substantiallyconverged upon a neighborhood of the rear side focus of the projectionlens, it is possible to enhance a ratio of utilizing the flux of lightsent from the light emitting element. In this case, the reflector may beattached to the unit support member separately from the light controlmember and the light emitting element. Alternatively, the reflector maybe attached to the unit support member together with the light controlmember and the light emitting element.

In this case, when each of the rectilinear propagation blocking membersof at least some of lighting device units has a reflecting face, thesurface profile of which is predetermined, extending from theneighborhood of the rear side focus of the projection lens to the rearside, the ratio of utilizing the flux of light emitted from the lightemitting element can be further enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing a vehicle headlight of an embodiment ofthe present invention.

FIG. 2 is a sectional view taken on line II-II in FIG. 1.

FIG. 3 is a sectional view taken on line III-III in FIG. 2.

FIG. 4 is an enlarged view showing a primary portion of FIG. 2 in whicha lighting device unit for medium diffusion of the vehicle headlight isshown in detail.

FIG. 5 is a sectional side view showing the lighting device unit formedium diffusion in detail.

FIG. 6 is a sectional plan view showing the lighting device unit formedium diffusion in detail.

FIG. 7 is a sectional view taken on line VII-VII in FIG. 4.

FIG. 8 is an exploded perspective view for explaining an attachingstructure of attaching the lighting device unit for medium diffusion toa unit support member.

FIG. 9 is a view showing a lighting device unit for condensing light ofthe vehicle headlight in detail, wherein FIG. 9 is drawn in the samemanner as that of FIG. 6.

FIG. 10 is a view showing a lighting device unit for wide diffusion ofthe vehicle headlight in detail, wherein FIG. 10 is drawn in the samemanner as that of FIG. 6.

FIG. 11 is a perspective view showing a light distribution pattern for alow beam formed on a virtual perpendicular screen, which is arrangedahead at a position distant from a lighting device by 25 m, by a beam oflight irradiated ahead by the vehicle headlight.

FIGS. 12A to 12C are views showing light distribution patterns composinga portion of the light distribution pattern for a low beam, wherein FIG.12A is a view showing a light distribution pattern formed by theirradiation of light sent from the lighting device unit for mediumdiffusion, FIG. 12B is a view showing a light distribution patternformed by the irradiation of light sent from the lighting device unitfor condensing light and FIG. 12C is a view showing a light distributionpattern formed by the irradiation of light sent from the above lightingdevice unit for wide diffusion.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, an embodiment of the present invention willbe explained below.

FIG. 1 is a front view showing a vehicle headlight of an embodiment ofthe present invention. FIG. 2 is a sectional view taken on line II-II inFIG. 1. FIG. 3 is a sectional view taken on line III-III in FIG. 2.

As shown in these drawings, the vehicle headlight 10 of this embodimentis a lighting device arranged on the right of a front end portion of avehicle. The vehicle headlight 10 is composed in such a manner thateight lighting device units 30, 50, 70, four of them are arranged in theupper step and the other four of them are arranged in the lower step,are accommodated in a lighting chamber including a lamp body 12 and atransparent light transmission cover 14 attached to the front endopening of the lamp body 12. In this vehicle headlight 10, a lightdistribution pattern for a low beam can be formed by the irradiation oflight sent from these eight lighting device units 30, 50, 70.

In the above light chamber, an inner panel 16 is arranged along thelight transmission cover 14. At positions on the inner panelcorresponding to the lighting device units 30, 50, 70, the cylindricalopening portions 16 a surrounding the lighting device units 30, 50, 70are formed.

All of the eight lighting device units 30, 50, 70 are composed as aprojector type lighting device unit. While these eight lighting deviceunits 30, 50, 70 are being attached to the common support member 20,they are tiltably supported by the lamp body 12 via the aiming mechanism22 so that these eight lighting device units 30, 50, 70 can be tilted inthe vertical and the traverse direction.

The unit support member 20 is composed of a die-cast product, forexample, an aluminum die-cast product. The unit support member 20includes: a perpendicular panel portion 20A; a unit attaching portion20B extending like a shelf to the front from the perpendicular panelportion 20A at a plurality of portions; and a heat sink portion 20Ccomposed of a plurality of radiating fins extending from theperpendicular panel portion 20A to the rear.

The heat sink portion 20C is arranged at two portions, one is a rightportion and the other is a left portion. The right and the left heatsing portion are protruded from the two circular opening portions 12 a,which are formed on a rear wall of the lamp body 12, to the outer spaceof the lighting device. A rubber cover 18 for sealing is attached toeach opening portion 12 a. An inner circumferential portion of therubber cover 18 is engaged with an outer circumferential base endportion of the heat sink portion 20C, and an outer circumferentialportion of the rubber cover 18 is engaged with the opening portion 12 aof the lamp body 12.

The optical axes A_(x) of the lighting device units 30, 50, 70 areextended in parallel with each other in the direction substantiallyperpendicular to the perpendicular panel portion 20A. After the opticalaxis adjustment made by the aiming mechanism 22 has been completed, theoptical axes A_(x) of the lighting device units 30, 50, 70 are extendedin a downward direction by an angle 0.5 to 0.6° with respect to thelongitudinal direction of a vehicle.

The three lighting device units 30, which are among the eight lightingdevice units 30, 50, 70 and located on the outside in the vehicle widthdirection in the upper step, are composed as lighting device units formedium diffusion. The three lighting device units 50, which are amongthe eight lighting device units 30, 50, 70 and located on the outside inthe vehicle width direction in the lower step, are composed as lightingdevice units for condensing light. The two lighting device units 70,which are located at the end portions on the inside in the vehicle widthdirection in the upper and the lower step, are composed as lightingdevice units for wide diffusion.

Next, the specific structure of the lighting device units 30, 50, 70will be explained below.

First, the specific structure of the lighting device units 30 for mediumdiffusion will be explained as follows.

FIG. 4 is an enlarged view showing a primary portion of FIG. 2 in whichthe lighting device unit 30 for medium diffusion is shown in detail.FIGS. 5 and 6 are the sectional side view and the sectional plan view.FIG. 7 is a sectional view taken on line VII-VII in FIG. 4. FIG. 8 is anexploded perspective view for explaining an attaching structure in whichthe lighting device unit 30 for medium diffusion is attached to the unitsupport member 20.

As shown in these drawings, the lighting device unit 30 for mediumdiffusion includes: a projection lens 32 arranged on the optical axisA_(x); a light emitting element 34 arranged at the rear of thisprojection lens 32; a reflector 36 arranged so that the reflector 36 cancover this light emitting element 34 from the upper side; and arectilinear propagation blocking member 38 arranged between the lightemitting element 34 and the projection lens 32.

In this lighting device unit 30 for medium diffusion, the projectionlens 32 and the rectilinear propagation blocking member 38 areintegrally formed as a light control member 40 by means of insertionmolding. In this lighting device unit 30 for medium diffusion, the lightemitting element 34, the reflector 36 and the light control member 40are individually attached to the unit attaching portion 20B of the unitsupport member 20. In this way, the lighting device unit is composed.

The projection lens 32 is a transparent lens made of resin (for example,a transparent lens made of acrylic resin) which is composed as aplano-convex lens, the front surface of which is formed into a convexand the rear surface of which is formed into a plane. The focal distanceof the projection lens 32 is f1, which is relatively short.

The light emitting element 34 is a white light emitting diode having alight emitting chip 34 a, the size of which is approximately 0.3 to 1 mmsquare, and supported by the support plate 42 made of metal, the shapeof which is a regular hexagon. This light emitting element 34 isattached to the unit attaching portion 20B of the unit support member 20under the condition that the light emitting chip 34 a is arranged beingdirected perpendicularly upward on the optical axis A_(x).

The reflector 36 is composed in such a manner that the light emittedfrom the light emitting element 34 is reflected to the front side beingdirected to the optical axis A_(x) side, so that the light can besubstantially converged upon the neighborhood of the rear side focus Fof the projection lens 32. Specifically, the reflecting face 36 a ofthis reflector 36 is set in such a manner that the cross section of thereflector 36 including the optical axis A_(x) is formed into asubstantial elliptical shape and that the eccentricity is graduallyincreased from the perpendicular cross section to the horizontal crosssection. This reflecting face 36 a is formed so that the light sent fromthe light emitting element 34 can be substantially converged at aposition somewhat ahead of the rear side focus F.

This reflector 36 includes a pair of brackets 36 b, one is arranged onthe right and the other is arranged on the left. This reflector 36 isfixed being screwed to the unit support member 20 in both the brackets36 b under the condition that the peripheral lower end portion is madeto come into contact with an upper face of the unit attaching portion20B of the unit support member 20.

The rectilinear propagation blocking member 38 is a transparent membermade of resin (for example, a member made of resin of polycarbonate).This rectilinear propagation blocking member 38 includes: a main body38A, the upper face 38 a of which is formed into a substantial C-shapewhen it is viewed from the front of the lighting device; and a lensholder portion 38B formed being extended from the front end portion ofthe main body 38A to the front of a vehicle.

The upper face 38 a of the main body 38A extends to the rear from therear side focus F of the projection lens 32, and the front end edge 38 a1 of the main body 38A is formed into a substantial arc shape along thefocal face of the rear side focus F of the projection lens 32. Thisupper face 38 a is formed as follows. A region on the left (on the rightwhen it is viewed from the front of the lighting device) with respect tothe optical axis A_(x) is composed of a plane horizontally extending tothe left from the optical axis A_(x), and a region on the right withrespect to the optical axis A_(x) is composed of a plane extending fromthe optical axis A_(x) to the right obliquely downward (for example, bythe angle 15° downward). This upper face 38 a is subjected to reflectingface treatment by means of aluminum vapor deposition. Due to theforegoing, a portion of the reflected light sent from the reflectingface 36 a of the reflector 36 is prevented from propagating straight bythe upper face 38 a. The upper face 38 a is composed as a reflectingface on which the portion of the reflected light sent from thereflecting face 36 a is reflected upward.

The lens holder 38B extends to the front from the front end portion ofthe main body 38A so that it can be curved downward. The lens holder 38Bsupports the projection lens 32 by the semicircular positioning groove38 b formed in the front end portion of the lens holder 38B. Asdescribed before, this fixing and supporting action can be conductedwhen the projection lens 32, the rectilinear propagation blocking member38 and the light control member 40 are integrally formed by means ofinsertion molding. At this time, while the projection lens 32 is beinginserted, the rectilinear propagation blocking member 38 is made bymeans of injection molding.

In the rectilinear propagation blocking member 38, a pair of brackets 38c, one is arranged on the right and the other is arranged on the left,are formed at the rear end portion of the main body 38A. In a lowerportion of the main body 38A of the rectilinear propagation blockingmember 38, the positioning pin 38 d protruding from the lens holder 38Bto the rear is formed. Between the positioning pin 38 d and the mainbody 38A, the perpendicular rib 38 e for connecting both the positioningpin 38 d and the main body 38A is formed.

On the other hand, the unit attaching portion 20B of the unit supportmember 20 includes: a light source fixing portion 20B1 for fixing andsupporting the light emitting element 34; a pair of boss portions 20B2arranged on both sides of this light source fixing portion 20B1 whileleaving a predetermined interval; a reflector support portion 20B3arranged between the pair of boss portions 20B2; and a pin receivingportion 20B4 arranged in a lower portion of the light source fixingportion 20B1. The front end face 20 a of the unit support member 20 iscomposed of a plane parallel with the perpendicular panel portion 20Awhich is perpendicular to the metallic die releasing direction of theunit support member 20.

The reflector support portion 20B3 of this unit attaching portion 20B isformed into a substantial C-shape when it is viewed from the front ofthe lighting device so that an upper face of the reflector supportportion 20B3 can be on the same face as the upper face 38 a of therectilinear propagation blocking member 38.

The pin receiving portion 20B4 of this unit attaching portion 20B isformed at a position opposing to the positioning pin 38 d of therectilinear propagation blocking member 38. Between the pin receivingportion 20B4 and the light source fixing portion 29B1, the perpendicularrib 20 c for connecting both of them is provided.

The rectilinear propagation blocking member 38 is screwed and fixed tothe unit support member 20 in both the bracket portions 38 c under thecondition that each bracket 38 c and the positioning pin 38 d of themain body 38A are made to come into contact with the front end face 20 aof the unit attaching portion 20B of the unit support member 20 at thepositions of each boss portion 20B2 and the pin receiving portion 20B4.

The above screwing fixation is conducted when the rectilinearpropagation blocking member 38 and the reflector 36 are fastened to eachother. In order to realize this screwing fixation, the screw insertionholes 36 b 1, 38 c 1 for inserting the screw 44 are formed in eachbracket 36 b of the reflector 36 and each bracket 38 c of therectilinear propagation blocking member 38 on the same straight line. Onthe front end face 20 a of the unit attaching portion 20B of the unitsupport member 20, the screw hole 20 b is formed at the position of eachboss portion 20B2.

In each bracket 38 c of the rectilinear propagation blocking member 38,the spherical protruding portion 38 c 2 is formed in the neighborhood ofthe upper portion of the screw insertion hole 38 c 1 on the rear face.Due to the foregoing, the screwing fixation of the rectilinearpropagation blocking member 38 can be conducted under the condition thatthree portion of the rectilinear propagation blocking member 38 arecontacted with the unit support member 20.

As shown in FIG. 7, a fastening force given at the time of the fixationby screwing acts as a resultant force at the attaching center P of therectilinear propagation blocking member 38, that is, at the middle pointof the line segment connecting the centers of a pair of screw holes 20 bof the unit support member 20. This attaching center P is located at thesubstantial center of a triangle formed by the center of the positioningpin 38 d and the centers of the pair of spherical protruding portions 38c 2. Therefore, the rectilinear propagation blocking member 38 can beaccurately, stably attached to the unit support member 20 by thethree-point support structure.

As described before, in the present embodiment, the projection lens 32and the rectilinear propagation blocking member 38 are formed integrallywith each other so that the light control member 40 can be formed.Therefore, when the rectilinear propagation blocking member 38 isattached to the unit support member 20, the projection lens 32 can besimultaneously attached to the unit support member 20.

On the other hand, the light emitting element 34 is fixed to the unitsupport member 20 in such a manner that the support plate 42 forsupporting the light emitting element 34 is press-fitted into the recessgroove portion 20 d, which is formed in the light source fixing portion20B1 of the unit attaching portion 20B, from the front side.

Next, the specific structure of the lighting device unit 50 forcondensing light will be explained below.

FIG. 9 is a sectional plan view showing the detail of the lightingdevice unit 50 for condensing light.

As shown in the drawing, the constitution of the light emitting element54 and the reflector 56 of the lighting device unit 50 for condensinglight is completely the same as the constitution of the light emittingelement 34 and the reflector 36 of the lighting device unit 30 formedium diffusion. Further, the light control member 60 of the lightingdevice unit 50 for condensing light is completely the same as the lightcontrol member 40 of the lighting device unit 30 for medium diffusionexcept for the following points.

The focal distance f2 of the projection lens 52 of the light controlmember 60 is longer than the focal distance f1 of the projection lens 32of the lighting device unit 30. Corresponding to that, the longitudinallength of the lens holder 58B of the rectilinear propagation blockingmember 58 of the light control member 60 is longer than the length ofthe lens holder portion 38B of the lighting device unit 30.

In the same manner as that of the lighting device unit 30 for mediumdiffusion, when the light emitting element 54, the reflector 56 and thelight control member 60 of the lighting device unit 50 for condensinglight are individually attached to the unit attaching portion 20B of theunit supporting member 20, the lighting device unit can be completed.

Next, the specific structure of the lighting device unit 70 for a widediffusion will be explained below.

FIG. 10 is a sectional plan view showing the detail of the lightingdevice unit 70 for a wide diffusion.

As shown in the drawing, the structure of the light emitting element 74and the projection lens 72 of the light control member 80 of thislighting device unit 70 for wide diffusion is completely the same asthat of the light emitting element 34 and the projection lens 32 of thelighting device unit 30 for medium diffusion. The structure of thereflector 76 and the rectilinear propagation blocking member 78 of thelight control member 80 is completely the same as that of the reflector36 and the rectilinear propagation blocking member 38 of the lightingdevice unit 30 for medium diffusion except for the following points.

The essential structure of the reflector 76 is the same as that of thereflector 36. The reflecting face 76 a of this reflector 76 is set insuch a manner that the cross section of the reflector 76 including theoptical axis A_(x) is formed into a substantial elliptical shape andthat the eccentricity is gradually increased from the perpendicularcross section to the horizontal cross section. In this case, a ratio ofthe increase in the eccentricity of the reflecting face 76 a is highcompared with the case of the reflector 36. Therefore, the lateral widthof the reflector 76 is larger than the lateral width of the reflector36.

The essential structure of the rectilinear propagation blocking member78 is the same as that of the rectilinear propagation blocking member38. The upper face 78 a of the main body 78A of the rectilinearpropagation blocking member 78 is extended to the rear from the rearside focus F of the projection lens 72. This upper face 78 a issubjected to the reflecting face treatment. All region of this upperface 78 a is composed of a horizontal face including the optical axisA_(x). According to that, the peripheral lower end portion of thereflector 76 and the upper face of the reflector support portion 20B3 ofthe unit support member 20 are formed into a horizontal face.

In the same manner as that of the lighting device unit 30 for mediumdiffusion, when the light emitting element 74, the reflector 76 and thelight control member 80 of the lighting device unit 70 for widediffusion are individually attached to the unit attaching portion 20B ofthe unit supporting member 20, the lighting device unit can becompleted.

FIG. 11 is a perspective view showing a light distribution pattern for alow beam formed on a virtual perpendicular screen, which is arrangedahead at a position distant from a lighting device by 25 m, by a beam oflight irradiated ahead by the vehicle headlight 10 of the presentembodiment.

As shown in the drawing, this light distribution pattern PL for a lowbeam is a light distribution pattern in which light is distributed tothe left. This light distribution pattern PL for a low beam includes:the horizontal cutoff line CL1 at the upper end edge; and the obliquecutoff line CL2 which rises from this horizontal cutoff line CL1 by apredetermined angle (for example, 15°). A position of the elbow point E,which is an intersection of both the cutoff lines CL1 and CL2, is set ata position lower than H-V, which is a vanishing point in the frontdirection of the lighting device, by the angle of 0.5 to 0.6°. In thislight distribution pattern PL for a low beam, the hot zone HZL, which isa region of high luminous intensity, is formed surrounding the elbowpoint E.

This light distribution pattern PL for a low beam is formed as acompound light distribution pattern including: three light distributionpatterns PL1 for medium diffusion formed by the irradiation of lightsent from three lighting device units 30 for medium diffusion; threelight distribution patterns PL2 for condensing light formed by theirradiation of light sent from three lighting device units 50 forcondensing light; and two light distribution patterns PL3 for widediffusion formed by the irradiation of light sent from two lightingdevice units 70 for wide diffusion.

As shown in FIG. 12A, in the light distribution pattern PL1 for mediumdiffusion formed by the irradiation of light sent from the lightingdevice unit 30 for medium diffusion, as a reverse projected image of thefront end edge 38 a 1 of the upper face 38 a of the main body 38A of therectilinear propagation blocking member 38, the horizontal cutoff lineCL1 and the oblique cutoff line CL2 are formed. In this case, the upperface 38 a of the main body 38A is composed as a reflecting face.Therefore, as shown by the two-dotted chain line in FIG. 5, a beam oflight, which is to be emergent upward from the projection lens 32, inthe reflected light reflected on the reflecting face 36 a of thereflector 36 can be utilized as a beam of light, which is emergentdownward from the projection lens 32 as shown by the solid line in thedrawing, by the reflecting action of the upper face 38 a. Due to theforegoing, a ratio of utilizing the luminous flux of the light emergentfrom the light emitting element 34 can be enhanced, and further the hotzone HZL1 can be formed.

As shown in FIG. 12B, in the light distribution pattern PL2 forcondensing light formed by the irradiation of light sent from thelighting device unit 50 for condensing light, as a reverse projectedimage of the front end edge 58 a 1 of the upper face 58 a of the mainbody 58A of the rectilinear propagation blocking member 58, thehorizontal cutoff line CL1 and the oblique cutoff line CL2 are formed.In this case, the upper face 58 a of the main body 38A is composed as areflecting face. Therefore, a beam of light, which is to be emergentupward from the projection lens 52, in the reflected light reflected onthe reflecting face 56 a of the reflector 56 can be utilized as a beamof light which is emergent downward from the projection lens 52. Due tothe foregoing, a ratio of utilizing the luminous flux of the lightemergent from the light emitting element 54 can be enhanced, and furtherthe hot zone HZL2 can be formed.

Since the focal distance f2 of the projection lens 52 is longer than thefocal distance f1 of the projection lens 32, the light distributionpattern PL2 for condensing light is smaller and brighter than the lightdistribution pattern PL1 for medium diffusion. The hot zone HZL2 issmaller and brighter than the hot zone HZL1 of the light distributionpattern PL1 for medium diffusion.

On the other hand, in the light distribution pattern PL3 for widediffusion formed by the irradiation of light sent from the lightingdevice unit 70 for wide diffusion, as a reverse projected image of thefront end edge 78 a 1 of the upper face 78 a of the main body 78A of therectilinear propagation blocking member 78, the horizontal cutoff lineCL1 is formed. In this case, the upper face 78 a of the main body 78A iscomposed as a reflecting face. Therefore, a beam of light, which is tobe emergent upward from the projection lens 72, in the reflected lightreflected on the reflecting face 76 a of the reflector 76 can beutilized as abeam of light, which is emergent downward from theprojection lens 72, by the reflecting action of the upper space 78 a.Due to the foregoing, a ratio of utilizing the luminous flux of thelight emergent from the light emitting element 74 can be enhanced, andfurther the hot zone HZL3 can be formed.

In the light distribution pattern PL2 for wide diffusion, a ratio of thechange of the eccentricity of the reflecting face 76 a of the reflector76 from the perpendicular cross section to the horizontal cross sectionis set to be higher than that of the reflector 36. Therefore, thediffusion angle in the traverse direction of the light distributionpattern PL2 is larger than that of the light distribution pattern PL1.In this connection, only the horizontal cutoff line CL1 is formed on theupper end edge of the light distribution pattern PL3 for wide diffusion,and the oblique cutoff line CL2 is not formed. The reason is that theupper face 78 a of the main body 78A of the rectilinear propagationblocking member 78 is formed to be a horizontal face.

As the detail are described above, in the vehicle headlight 10 of thepresent embodiment, by the irradiation of light sent from the eightlighting device units 30, 50, 70, the light sources of which are thelight emitting elements 34, 54, 74, the light distribution pattern PLfor a low beam is formed which has the horizontal cutoff line CL1 andthe oblique cutoff line CL2 at the upper end edge. Therefore, thethickness of the lighting device can be reduced.

Since these eight lighting device units 30, 50, 70 are supported by thecommon unit support member 20, when this unit support member 20 istilted, the optical axes of these eight lighting device units 30, 50, 70can be simultaneously adjusted.

In each lighting device unit 30, 50, 70, the projection lens 32, 52, 72and the rectilinear propagation blocking member 38, 58, 78, whichcompose the lighting device unit 30, 50, 70, are integrally formed as alight control member 40, 60, 80, and the light control member 40, 60, 80and the light emitting element 34, 54, 74 are individually attached tothe unit support member 20. Therefore, the following operational effectscan be provided.

In the lighting device unit 30, 50, 70 composed in such a manner that aportion of light emitted from the light emitting element 34, 54, 74 isprevented from propagating straight by the rectilinear propagationblocking member 38, 58, 78 arranged in the neighborhood of the rear sidefocus F of the projection lens 32, 52, 72, in order to form a clearcutoff line at a predetermined position with high accuracy, it is veryimportant to ensure the accuracy of the positional relation between theprojection lens 32, 52, 72 and the rectilinear propagation blockingmember 38, 58, 78. On the other hand, the accuracy of the positionalrelation between them and the light emitting element 34, 54, 74 is notso important.

Therefore, as described in the present embodiment, when the projectionlens 32, 52, 72 and the rectilinear propagation blocking member 38, 58,78, the accuracy of the positional relation of which must be high, areintegrally formed as a light control member 40, 60, 80 and when thelight control member 40, 60, 80 and the light emitting element 34, 54,74 are individually attached to the unit support member 20, the lightingdevice unit 30, 50, 70 can be completed without affecting the lightdistribution performance of the lighting device unit 30, 50, 70. Whenthe components of the lighting device unit 30, 50, 70 are individuallyattached to the unit support member 20, the lighting device structurecan be made simple compared with a case in which the completed lightingdevice unit is attached to the unit support member 20.

As described above, in the present embodiment, while the thickness ofthe lighting device is being reduced, the optical axes of the eightlighting device units 30, 50, 70 can be simultaneously adjusted withoutmaking the structure of the lighting device complicated.

In this case, in the present embodiment, eight lighting device units 30,50, 70 are composed of three types of units.

They are the lighting device units 30 for medium diffusion, the lightingdevice units 50 for condensing light and the lighting device units 70for wide diffusion. Therefore, the light distribution pattern PL for alow beam formed by these lighting device units can be formed as acompound light distribution pattern including the light distributionpattern PL1 for medium diffusion, the light distribution pattern PL2 forcondensing light and the light distribution pattern PL3 for widediffusion. Due to the foregoing, the luminous intensity of the lightdistribution pattern PL for a low beam can be made uniform.

Further, in the present embodiment, since the unit support member 20 iscomposed of a die-cast product, the following operational effects can beprovided.

When the light emitting element 34, 54, 74 of each lighting device unit30, 50, 70 emits light, heat is generated from the light emittingelement. However, since each light emitting element 34, 54, 74 isattached to the unit support member 20 composed of a die-cast product,heat generated by each light emitting element 34, 54, 74 can be quicklytransmitted to the unit support member 20, the heat capacity of which islarge, by the action of heat conduction. Due to the foregoing, atemperature rise of the light emitting element 34, 54, 74 can besuppressed. Therefore, it is possible to effectively prevent theluminous flux of the light emitting element 34, 54, 74 from beingdecreased. It is also possible to prevent the color of emitted lightfrom becoming discolored.

In the present embodiment, since the light control member 40, 60, 80 iscomposed of an insertion molded product, the following operationaleffects can be provided.

As described in the present embodiment, when the insertion molding isconducted after the projection lens 32, 52, 72 has been inserted, it ispossible to integrate the projection lens 32, 52, 72 and the rectilinearpropagation blocking member 38, 58, 78 into one body by the insertionmolding after the projection lens 32, 52, 72 has been previously formedas a single body. Due to the foregoing, after the profile accuracy ofthe projection lens 32, 52, 72 has been sufficiently ensured, theaccuracy of the positional relation between the projection lens 32, 52,72 and the rectilinear propagation blocking member 38, 58, 78 can besufficiently enhanced.

In the present embodiment, since each of the eight lighting device units30, 50, 70 includes a reflector 36, 56, 76 for reflecting a beam oflight, which is sent from the light emitting element 34, 54, 74, forwardso that the beam of light can be substantially converged upon aneighborhood of the rear side focus F of the projection lens 32, 52, 72,it is possible to enhance a ratio of utilizing the flux of light sentfrom the light emitting element 34, 54, 74. In this case, the reflector36, 56, 76 is attached to the unit support member 20 by screwingsimultaneously when the light control member 40, 60, 80 is screwed andfixed to the unit support member 20. Therefore, the assembling propertyof assembling the lighting device unit 30, 50, 70 can be enhanced.

In this embodiment, when each of the eight lighting device units 30, 50,70 has a reflecting face 38 a, 58 a, 78 a, the surface profile of whichis predetermined, extending from the neighborhood of the rear side focusF of the projection lens 32, 52, 72 to the rear side, a ratio ofutilizing the flux of light emitted from the light emitting element 34,54, 74 can be further enhanced.

In this connection, instead of adopting the constitution in which thelighting device unit 30, 50, 70 is composed into a projector typelighting device unit having the reflector 36, 56, 76, it is possible toadopt the constitution in which a light-shielding member having apredetermined upper end edge profile corresponding to a cutoff line isarranged as a rectilinear propagation blocking member in theneighborhood of the rear side focus F of the projection lens 32, 52, 72and a light emitting element is arranged in the neighborhood at the rearof the light-shielding member.

In the above embodiment, the size of the light emitting chip 34 a of thelight emitting element 34 is approximately 0.3 to 1 mm square. However,it is possible to form the light emitting chip 34 a of the lightemitting element 34 into the other size and profile. Examples of thesize and profile of the light emitting chip 34 a of the light emittingelement 34 are: a rectangle, the short side of which is 1 mm and thelong side of which is 2 mm; and a rectangle, the short side of which is1 mm and the long side of which is 4 mm. The circumstances are the samewith respect to the light emitting chips of the other light emittingelements 54, 74.

In the above embodiment, the vehicle headlight includes: three lightingdevice units 30 for medium diffusion; three lighting device units 50 forcondensing light; and two lighting device units 70 for wide diffusion.However, the numbers of these lighting device units are not limited tothe above. Of course, any number of the lighting device units except forthe aforementioned numbers can be adopted.

In the vehicle headlight 10 of the above embodiment, only the lightingdevice unit 30, 50, 70 for forming a light distribution pattern for alow beam is accommodated in the lighting chamber. However, of course,the lighting device unit for forming a light distribution pattern for ahigh beam can accommodated in the lighting chamber.

In the above embodiment, explanations are made into the vehicleheadlight 10 arranged on the right of the front end portion of avehicle. However, concerning the vehicle headlight arranged on the leftof the front end portion of the vehicle, when the same constitution asthat of the above embodiment is adopted, the same operational effects asthose of the above embodiment can be provided.

1. A headlight comprising: a plurality of lighting device units; and aunit support member that supports the plurality of lighting deviceunits, wherein each lighting device unit includes: a projection lens; alight emitting element arranged at the rear of the rear side focus ofthe projection lens; and a rectilinear propagation blocking member thatis arranged in the neighborhood of the rear side focus, and blocks arectilinear propagation of a portion of light emitted from the lightemitting element so as to form the cutoff line, wherein the projectionlens and the rectilinear propagation blocking member are integrallyformed as a light control member, and wherein the light control memberand the light emitting element are individually attached to the unitsupport member.
 2. The headlight according to claim 1, wherein apredetermined light distribution pattern is formed when light isirradiated by the plurality of lighting device units, and wherein thepredetermined light distribution pattern has a cutoff line formed at anupper end edge of the predetermined light distribution pattern.
 3. Theheadlight according to claim 1, wherein the unit support membercomprises a die-cast product.
 4. The headlight according to claim 1,wherein the light control member comprises an insertion molded product.5. The headlight according to claim 1, wherein at least one of theplurality of lighting device units includes a reflector, and wherein abeam of light sent from the light emitting element is reflected by thereflector forward and is substantially converged upon a neighborhood ofthe rear side focus.
 6. The headlight according to claim 5, wherein therectilinear propagation blocking member of the one of the plurality oflighting device units includes a reflecting face, wherein a surfaceprofile of the reflecting face is extending from the neighborhood of therear side focus to the rear, and the light sent from the reflector isreflected on the reflecting face.